For a variety of reasons, the enamel surfaces of teeth sometimes become permanently stained, decayed or damaged. A technique has been developed to repair or improve the appearance and function of such teeth.
In a procedure referred to as cosmetic bonding, a thin veneer of ceramic or plastic having a shape and curvature matching the outline, shape and surface curvature of a tooth to be refaced is bonded to the facial or labial surface of the tooth, after the tooth has been specially prepared. The veneer has a desired surface coloration and gloss to match adjacent teeth. The veneer is sufficiently opaque to mask a stained surface of the underlying tooth. By this procedure, teeth may be restored to a more pleasing and functional appearance.
Cosmetic bonding includes a sequence of steps requiring exercise of a substantial degree of artistic craftsmanship. The dentist must prepare each tooth to receive a veneer and make accurate impressions of the prepared teeth. Teeth impressions are made by forming a dental impression material over the teeth and allowing the material to harden. Impressions are then used by a dental ceramist or a dentist to make a veneer. In one procedure the impressions are used to make molds in which the required ceramic veneers are eventually fabricated. Each veneer is individually fabricated and must have the desired precise dimensions, coloration, luster, and opacity.
The number of individually demanding steps required to fabricate each tooth veneer results in a substantial investment in time. Thus, the replacement value of each custom-made veneer is significant. Accordingly, considerable care must be exercised in handling a veneer to avoid damage to it. The veneer is relatively fragile until it has been bonded or laminated to and supported by the tooth for which it was custom-fabricated.
After a number of preparation steps, the veneer is temporarily placed on the appropriate tooth. The purpose of the temporary placement is to check size, opacity and coloration of the veneer. After this preliminary testing, the veneer is removed, and both the veneer and tooth thoroughly cleaned of the temporary adhesive and dried. The veneer or other restoration is then permanently bonded to the supporting tooth. Typically this is done with a light sensitive bonding agent. The inner surface of the restoration is coated with such bonding agent, and the restoration placed in position on the tooth. All of these procedures are usually performed by the dentist holding the substantially small, fragile restoration between his or her thumb and forefinger. Needless to say, many of these small restorations are inadvertently dropped or damaged during the fitting, adjustment and placement phase.
Another difficulty encountered in positioning and permanently bonding a restoration to a tooth concerns the permanent bonding agent employed. One type that is frequently utilized is a composite resin that is fairly viscous or stiff. The material should, of course, be spread between all of the mating surfaces of the restoration and the base tooth. It is also desirable that any excess bonding agent be squeezed out from between the restoration and the tooth. In one current attempt at accomplishing this, the dentist will press a finger on the restoration and roll the finger from side to side, while balancing the force with a finger on the backside of the tooth. This is not a very effective method. Dental crowns are sometimes seated using a vibrating pad clamped between the crown and the mating tooth and the opposing jaw. This method cannot be used with a veneer since there is no mating biting surface.
After the bonding agent spreading step is completed, the bonding agent is cured. Typically this is accomplished by irradiating the outer surface of the restoration with a small intense light source. Light transmitted through the restoration produces a photo-chemical reaction in the bonding agent, causing it to harden.
During the light exposure process, which takes between 20 and 60 seconds, the dentist must hold the restoration in a precisely aligned position with respect to the tooth. If the restoration is displaced from its aligned position during the bonding process, the restoration may have to be ground off the tooth, and a replacement restoration fabricated.
Because of the difficulty of handling and positioning the restoration, a variety of tools and techniques have been developed. These prior systems have various disadvantages such as complexity, difficulty in using or ineffectiveness. Thus, it is believed that many restorations are positioned only with fingers. Accordingly, a need exists for an improved, simplified tool and technique for handling veneers and other restorations. There is also a need for improving the means for spreading the bonding agent that joins the restoration to the underlying tooth.